The present invention relates to a process for the liquid phase acylation of aromatic compounds using a solid catalyst comprising indium halide. This invention particularly relates to a process for the acylation of aromatic compounds for preparing acylated aromatic compounds using a reusable solid catalyst comprising indium halide.
The process for this invention could be used for the preparation of acylated aromatic compounds, which are fine chemicals and/or used as intermediates in the preparation of fine chemicals or speciality chemicals in dyes and pharmaceutical industries and other chemical industries.
Prior art discloses both homogeneous and heterogeneous liquid phase processes based on Friedel-Crafts type reactions for the preparation of acylated aromatic compounds.
The Friedel-Crafts type acylation of aromatic compounds by various acylating agents using homogeneous Lewis Acid catalysts, such as AlCl3, BF3, ZnCl2 and other metal chlorides and protonic acid catalysts, such as H2SO4, H3PO4, HF, etc., are well known in the prior art (ref G. A. Olah, in Friedel-Crafts and related reactions: vol. III, Acylation and related reactions, Wiley-Interscience Publ., New York, 1964).
U.S. Pat. No. (5,476,970 (1995)) of Rains et al., discloses a homogeneous liquid phase process for the acylation of R1,R2C6H4 by R3R4C6H3COCl, wherein R1, R2, R3 and R4 are chemical groups, using FeCl3 catalyst at high pressures. French patent (FR 2768728 (1999)) and (FR 2768729 (1999)) of Baudry et al., discloses liquid phase homogeneous process for the benzoylation of anisole by benzoyl chloride using rare earth halides or uranyl halide.
Japanese Patent (JP 08277241, A2 (1996)) of Kunikata discloses a liquid phase process for the acylation of phenol by phenyl acetyl chloride using a homogeneous AlCl3 catalyst. Japanese Patent (JP 09059205, A2 (1997)) of Oono discloses the use of AlCl, as a homogeneous catalyst for the acylation of toluene with acetyl chloride at high pressure.
Japanese Patent (JP 2000086570, A2 (2000)) of Shoji et al., discloses a homogeneous liquid phase process for the acylation of toluene by acetyl fluoride using HF-BF, as a catalyst.
The main disadvantages of the Friedel-Crafts type acylation processes based on the use of above mentioned homogeneous acid catalysts are as follows:
1) The separation and recovery of the dissolved acid catalysts from the liquid reaction mixture is difficult.
2) The disposal of the used acid catalysts creates environmental pollution.
3) The homogeneous acid catalysts also pose several other problems such as high toxicity, corrosion, spent acid disposal and use of more than the, stoichiometric amount.
A few liquid phase processes for the acylation of aromatic compounds by acyl halides using solid catalysts are also known in the prior art.
Japanese Patent (JP 01089894, A2 (1995)) of Myata et al., discloses a liquid phase process for the acylation of toluene with benzoyl chloride using ammonium chloride treated H-beta zeolite catalyst under reflux for 3h to get para-acylated toluene with 28% yield. French Patent (FR 2745287, A1 (1997)) of Barbier et al. discloses the liquid phase acylation of anisole by benzoyl acloride under reflux using neodymium chloride deposited on montmorillonite K-10 clay.
Vincent et al., (ref Tetrahedron Lett. 35, 1994, 2601) discloses that H-ZSM-5 zeolite can catalyze the acylation by benzoyl chloride of phenol and anisole but not the acylation with benzoyl chloride of benzene and naphthalene at 120xc2x0 C. for 5 h.
Acylation of aromatic compound involves electrophilic substitution of H from the aromatic nucleus of the aromatic compound. It is well known in the prior art that the electrophilic substitution is favoured by the presence of electron donating groups. such as OH. alkyl, alkoxy, phenoxy. amine, alkyl amine, SH etc., in the aromatic compound. Whereas the electrophilic substitution is inhibited by the presence of electron withdrawing groups such halo, nitro, cyano, carboxy, aldehyde, etc., in the aromatic compound (ef. G.A.Olah, in Friedel-Crafts and related reactions, Wiley-Interscience Publ., New York, 1963).
Although some limitations of the homogeneous acid catalyzed process are overcome in the prior art heterogeneous solid catalyzed processes described above, the acylating activity of the solid acid catalysts used in the prior art processes is low, particularly for acylating aromatic compounds not containing electron donating groups, such as benzene, naphthalene, etc. Both the prior art homogeneous and heterogeneous acid catalysts are highly moisture sensitive, and hence demand moisture-free or thoroughly dried reactants, solvents and catalyst for the Friedel-Crafts type acylation processes. In presence of moisture in the reaction mixture homogeneous and heterogeneous catalysts show poor activity in the Friedel-Crafts processes. Hence, there is a great practical need for finding more efficient and also moisture insensitive solid catalyst for the acylation of aromatic compounds.
The main object of this invention is to provide a liquid phase process for the acylation of aromatic compounds, including those not containing electron donating groups using novel solid catalyst which has high activity not only when the aromatic ring activating groups (i.e. electron donating groups such as alkyl, alkoxy, hydroxy, phenoxy, etc.) are present in the aromatic ring to be acylated but also when the ring activating group in the aromatic ring to be acylated is absent, so that the reaction temperature is low and or time for completing the reaction is shot.
Another object of this invention is to provide a liquid phase process for the acylation of aromatic compounds, using a novel solid catalyst which is easily separable and reusable in the process.
Yet another object of this invention is to provide a solid catalyzed liquid phase process for the acylation of aromatic compounds event in the presence of moisture in the reacon mixture.
Accordingly the present invention provides a process for the liquid phase acylation of an aromatic compound (1) of the formula (R1,R2R3R4)xe2x80x94Dxe2x80x94H by an acylating agent (II) of the formula (R5R6R7)xe2x80x94Yxe2x80x94Z to produce corresponding acylated aromatic compound (III) of the formula ((R1, R2R3R4)xe2x80x94Dxe2x80x94Yxe2x80x94(R5R6R7), wherein D is an aromatic nucleus selected from side aromatic ring containing 6 C-atoms and 1 H-atom or fused two aromatic rings containing 10 C-atoms and 3 H-atoms and three fused aromatic rings containing 14 C-atoms and 5 H-atoms; R1, R2,R3 and R4 are chemical groups attached to the aromatic nucleus, D; Y is a nucleus of the acylating agent selected from the group consisting of Cxe2x80x94CO, CnH2nxe2x88x922CO, C6H2xe2x80x94CO, C6H2CnH2nxe2x80x94CO and C6H2CnHn2xe2x88x921(X)-CO; R5, R6 and R7 are chemical groups attached to the nucleus of acylating agent Y; Z is selected from Cl, Br and I; X is a halogen group; and n is an integer xe2x89xa71.0, using a solid catalyst (IV), comprising indium halide, represented by a formula MxIn1xe2x88x92xAy(a)/S wherein S is a porous catalyst support selected from clays, zeolites and zeolite-like materials; M is a metallic chemical element selected from the group consisting of Ga, Fe, Zn, Ti ox a mixture of two or more thereof; A is a non-metallic chemical element selected from the group consisting of Cl, Br, I, F and a mixture of two or more thereof, x is a mole fraction of M and is in the range from 0.01 to 0.99; y is the number of A atoms required to satisfy the valence requirement of MxIn1xe2x88x92x; and a is a loading of MxIn1xe2x88x92x A on the support S and is in the range of from 0.05 mmol.gxe2x88x921 to 5.0 mmol.gxe2x88x921; said process comprising:
i) pretreating said catalyst (IV) under vacuum or flow of an inert gas selected from nitrogen, helium and argon at a temperature in the range from 50xc2x0 C. to 300xc2x0 C. for a period sufficient to remove adsorbed moisture from the catalyst;
ii) contacting a liquid reaction mixture comprising said aromatic compound (I) and said acylating agent (II) in the presence or absence of a non-aqueous. solvent with the pretreated catalyst in a stirred batch reactor fitted with a reflux condenser under vigorous stirring, in the presence or absence of an inert gas bubbling through the reaction mixture, at following reaction conditions: weight ratio of catalyst (IV) to acylating agent (II) in the range from about 0.05 to about 5.0, mole ratio of aromatic compound to acylating agent in the range from about 0.1 to about 100, weight ratio of non-aqueous solvent to aromatic compound in the range from zero to about 100, reaction temperature in the range from about 10xc2x0 C. to about 300xc2x0 C., pressure at least 1.0 atm, gas hourly space velocity of inert gas bubbled through the liquid reaction mixture in the range from zero hxe2x88x921 to about 5000 hxe2x88x921 and reaction period in the range from about 0.02 h to about 100 h;
iii) cooling the reaction mixture to a temperature about 30xc2x0 C., removing said catalyst from the reaction mixture by filtration and then separating the reaction products from the reaction mixture, and optionally washing the used catalyst by non-aqueous solvent or aromatic substrate; and
iv) reusing the used catalyst for subsequent reaction batch.
In another embodiment of the invention, each of the R1, R2, R3 and R4 chemical groups is selected from the group consisting of hydrogen, alkane, olefinic, phenyl, alkoxy, phenoxy, hydroxyl, aldehydic, ketonic, amine, amide, thio and sulphonic acid groups.
In another embodiment of the invention, Z is Cl or Br.
In a further embodiment of the invention, each of the R5, R6, and R7 chemical groups is selected from hydrogen, alkane, olefinic, phenyl, halogen, nitro and cyano groups.
In another embodiment of the invention, the weight ratio of catalyst to acylating agent is in the range from about 0.1 to 1.0.
In another embodiment of the invention, the mole ratio of aromatic compound to acylating agent is in the range from 0.5 to 20.
In another embodiment of the invention, the weight ratio of non-aqueous solvent to aromatic compound is in the range from zero to 20.
In another embodiment of the invention, the reaction temperature is in to range from 20xc2x0 C. to 200xc2x0 C.
In another embodiment of the invention, the reaction period is preferably in the range from 0.1 h to 20 h.
In another embodiment of the invention, the space velocity of inert gas in the range from 50 hxe2x88x921 to 500 hxe2x88x921.
In another embodiment of the invention, M is selected from Ga Fe and a fixture thereof
In another embodiment of the invention, wherein A is Cl.
In another embodiment of the invention, the loading of metal halides a, on the support in the catalyst is in the range from 0.3 mmol.gxe2x88x921 to 3.0 mmol.gxe2x88x921.
In another embodiment of the invention, the catalyst support S is selected from mesoporous MCM-41 and montmorillonite clay.
In another embodiment of the invention, the non-aqueous solvent is selected from the group consisting of dichloroethane, nitrobenzene, nitromethane, chlorobenzene, n-hexane, -heptane and n-octane.
In a further embodiment of the invention, the non-aqueous solvents is selected form dichloroethane and nitrobenzene.
The main finding of this invention is that the said catalyst shows high activity in the acylation of aromatic compounds not only when the electron donating group, which is aromatic ring activating group, is present in the aromatic ring to be acylated, but also when the electron donating group is absent in the aromatic ring to be acylated, and hence the reaction temperature is low and/or the time required for completing the reactions is short.
Other important finding of this invention is that said solid catalyst can be separated easily and reused repeatedly in the process. Another important finding of this invention is that the acylation of aromatic compound over said catalyst occurs with high reaction rates even in the presence of moisture in the reaction mixture.